Niko Kovac stunned his future employer by leading Eintracht Frankfurt to a 3-1 win over Bayern Munich in the German Cup final on Saturday.
The Frankfurt coach, who has agreed to take over from the retiring Jupp Heynckes in Munich next season, oversaw a committed performance from his side crowned by two goals from the impressive Ante Rebic.
The Croatian striker scored early and late to cancel out Robert Lewandowski's equalizer for Bayern.
Bayern might have had a penalty in injury time, but referee Felix Zwayer decided otherwise after consulting video replays, and Mijat Gacinovic then sealed it on a counterattack for Frankfurt.
"It's unbelievable," said Frankfurt's Kevin-Prince Boateng, back in his Berlin hometown. "Everyone said we'd be beaten out of the stadium and we beat Bayern Munich out of the stadium."
It was Frankfurt's first title for 30 years, and its fifth German Cup also provided a ticket to the Europa League next season.
"We fought and whoever fights and believes in themselves will be rewarded. I'm so proud," Boateng said.
Kovac went one better after his side lost to Borussia Dortmund in last year's German season-ending showpiece.
"This year we have the positive feelings, the nice feelings," said Kovac, who struggled to hold back his tears.
"I'm sad to be leaving. I know where I'm going, but I've experienced two and a half wonderful years and what we delivered here was huge. I'm leaving a team with great character, great guys."
Heynckes was hoping to sign off with another domestic double, but there was to be no repeat for the 73-year-old coach who revitalized Bayern after coming out of retirement to replace the fired Carlo Ancelotti.
Lewandowski hit the crossbar early on but Rebic took Frankfurt's first chance minutes later when he forced James Rodriguez to lose the ball and received it back from Boateng before firing inside the post.
Lewandowski equalized minutes into the second half when Joshua Kimmich pulled the ball back for the Poland striker to score with a deflected shot.
Rebic grabbed his second in the 82nd minute after a long punt from Danny da Costa. The Croat headed the ball on despite a defender on either side and clipped it over the outrushing Sven Ulreich.
Frankfurt fans were infuriated when the video referee told Felix Zwayer to check it again as the ball came off Boateng's hand, but the goal stood.
Zwayer was again the center of attention in a furious finale when Boateng appeared to foul Javi Martinez, but the referee was not feeling generous on his 37th birthday and he declined to award Bayern what looked a clear penalty despite several replay viewings.
"We were lucky," Kovac acknowledged. "I think it's a penalty."
Instead, Zwayer gave Bayern a corner, but Gacinovic ran the length of the pitch and scored at the other end.
"For me it's a clear penalty," said Bayern sporting director Hasan Salihamidzic, who clashed with his friend Kovac as emotions took hold.